Slugs and Snails: Thwarting the Slimy Buggers

Slugs are not welcome guests in the garden.

Slugs and snails can be a problem predator for your plants. Lots of time has gone into testing methods of preventing slugs from getting to plants, including eggshells, citrus, oatmeal, beer, gravel, sharp rocks, ashes, sand, and even bits of glass.  Of all of those methods, ashes and sand seem to be the only ones that are truly effective. You can provide some protection for your plants by surrounding them with a moat of dry, gritty earth, or by ‘mulching’ with garden ashes.

For the moat of sand, you can try a variety of methods: coarse sand, a crushed up brick, coarse sand paper tacked down. . . be creative. Slugs and snails will not likely cross such a barrier because it dries up their mucous membranes which inhibits their ability to travel. If they attempt to cross the barrier it will slow them down a great deal and seriously compromise their health if not kill them outright. Sand is easily purchased from many places in bags, or by the square yard. I think even Wal-Mart carries sand, and Home Depot certainly does.

You can create a coarse moat around individual plants or the entire grow box; the thicker or wider the moat the better the protection. Just keep in mind that this only keeps slugs and snails out but doesn’t hurt or kill them if they’re already on your plants. Be sure to strip your plants of all the snails and slugs that you can find after you’ve installed a gritty moat around your plants.

Remember that the sand or grit has to be dry to work. If it rains, you may be out of luck.  When dry sand, or something like it, comes in contact with slugs or snails, the sand will naturally pull water or moisture. When sand pulls water from the slug’s body, it dries out their membranes. Slugs and snails need to stay moist to live, and it’s the dry grittiness in one form or another that you need.

Ashes work well in keeping slugs away from your plants, but you only want to use them if your soil is acidic.

Ashes seem to work well too, but there is one thing to consider with ashes.  Ashes are alkaline, and most plants prefer a soil that is slightly acidic (optimal is a pH of 6.8).  For soils that are already alkaline, ashes are not a possibility.  It’s easy to alkalize a soil, but it’s difficult to acidify a soil for very long, let alone permanently.  Ashes can be used around plants in rainier, more humid areas, but I certainly wouldn’t use them in an arid region.

One other thing: as many of you know, table salt (sodium chloride) will kill slugs and snails and it may seem like a good, cheap option for controlling them. It is not a good idea, however, for your gardens or landscapes. The sodium ion in sodium chloride is a clay deflocculating agent, meaning, that once in the soil, sodium will scatter clay particles and disallow the penetration and travel of water through the soil (read the article on Soil for further information).

Then there’s always the time-consuming method of picking slugs and snails off of your plants. That may seem tedious, but it’s very effective.